Showing papers by "University of Maine published in 2001"
University of California, San Diego1, Smithsonian Tropical Research Institute2, State Street Corporation3, University of Florida4, University of California, Davis5, Bates College6, Australian National University7, University of Oregon8, University of California, Santa Cruz9, James Cook University10, University of Chicago11, University of North Carolina at Chapel Hill12, National Museum of Natural History13, University of Maine14, University of California, Santa Barbara15
TL;DR: Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of over-fished species until they too were overfished or died of epidemic diseases related to overcrowding as mentioned in this paper.
Abstract: Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.
5,411 citations
TL;DR: Observations suggest that carbon nanotubes, with their rigid nonpolar structures, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
Abstract: Confinement of matter on the nanometre scale can induce phase transitions not seen in bulk systems1. In the case of water, so-called drying transitions occur on this scale2,3,4,5 as a result of strong hydrogen-bonding between water molecules, which can cause the liquid to recede from nonpolar surfaces to form a vapour layer separating the bulk phase from the surface6. Here we report molecular dynamics simulations showing spontaneous and continuous filling of a nonpolar carbon nanotube with a one-dimensionally ordered chain of water molecules. Although the molecules forming the chain are in chemical and thermal equilibrium with the surrounding bath, we observe pulse-like transmission of water through the nanotube. These transmission bursts result from the tight hydrogen-bonding network inside the tube, which ensures that density fluctuations in the surrounding bath lead to concerted and rapid motion along the tube axis7,8,9. We also find that a minute reduction in the attraction between the tube wall and water dramatically affects pore hydration, leading to sharp, two-state transitions between empty and filled states on a nanosecond timescale. These observations suggest that carbon nanotubes, with their rigid nonpolar structures10,11, might be exploited as unique molecular channels for water and protons, with the channel occupancy and conductivity tunable by changes in the local channel polarity and solvent conditions.
3,115 citations
920 citations
TL;DR: In this paper, the authors analyze US consumers' demand for environmental attributes of deregulated residential electricity services using results from a survey designed to elicit consumers' willingness to pay for such attributes and using results of a hedonic analysis of actual price premiums charged for green electricity in several deregulated markets.
538 citations
TL;DR: The results suggest that macroevolutionary transitions may ultimately arise through microevolution occasionally ‘writ large’ but are perhaps temporally characterized by microev evolution ‘ writes in fits and starts’.
Abstract: We compiled a database of microevolution on contemporary time scales in nature (47 source articles; 30 animal species), comprising 2649 evolutionary rates in darwins (proportional change per million years) and 2151 evolutionary rates in haldanes (standard deviations per generation). Here we demonstrate how quantitative rate measures can provide general insights into patterns and processes of evolution. The frequency distribution of evolutionary rates was approximately log-normal, with many slow rates and few fast rates. Net selection intensities estimated from haldanes were on average lower than selection intensities commonly measured directly in natural populations. This difference suggests that natural selection could easily accomplish observed microevolution but that the intensities of selection typically measured in nature are rarely maintained for long (otherwise observed evolutionary rates would be higher). Traits closely associated with fitness (life history traits) appear to evolve at least as fast as traits less closely tied to fitness (morphology). The magnitude of evolutionary difference increased with the length of the time interval, particularly when maximum rates from a given study were considered. This pattern suggests a general underlying tendency toward increasing evolutionary diversification with time. However, evolutionary rates also tended to decrease with time, perhaps because longer time intervals average increasingly disparate rates over time, or because evolution slows when populations approach new optima or as genetic variation is depleted. In combination, our results suggest that macroevolutionary transitions may ultimately arise through microevolution occasionally ‘writ large’ but are perhaps temporally characterized by microevolution ‘writ in fits and starts’.
347 citations
TL;DR: A before-after study was conducted using the empirical Bayes procedure, which accounts for regression to the mean and traffic volume changes that usually accompany conversion of intersections to roundabouts and suggests that roundabout installation should be strongly promoted as an effective safety treatment for intersections.
Abstract: Modern roundabouts are designed to control traffic flow at intersections without the use of stop signs or traffic signals. U.S. experience with modern roundabouts is rather limited to date, but in recent years there has been growing interest in their potential benefits and a relatively large increase in roundabout construction. This interest has created a need for data regarding the safety effect of roundabouts. Changes in motor vehicle crashes following conversion of 23 intersections from stop sign and traffic signal control to modern roundabouts are evaluated. The settings, located in seven states, are a mix of urban, suburban, and rural environments with the urban sample consisting of both single-lane and multilane designs and the rural sample consisting of only single-lane designs. A before-after study was conducted using the empirical Bayes procedure, which accounts for regression to the mean and traffic volume changes that usually accompany conversion of intersections to roundabouts. For the 23 inte...
335 citations
TL;DR: In this paper, mollusks from archaeological sites on the north and central coasts of Peru indicate that between ca. 5800 and 3200-2800 cal yr B.P., El Nino events were less frequent than today, with modern, rapid recurrence intervals achieved only after that time.
Abstract: Analysis of mollusks from archaeological sites on the north and central coasts of Peru indicates that between ca. 5800 and 3200–2800 cal yr B.P., El Nino events were less frequent than today, with modern, rapid recurrence intervals achieved only after that time. For several millennia prior to 5.8 ka, El Nino events had been absent or very different from today. The phenomena called El Nino have had severe consequences for the modern and colonial (historically recorded) inhabitants of Peru, and El Nino events also influenced prehistoric cultural development: the onset of El Nino events at 5.8 ka correlates temporally with the beginning of monumental temple construction on the Peruvian coast, and the increase in El Nino frequency after 3.2–2.8 ka correlates with the abandonment of monumental temples in the same region.
329 citations
TL;DR: The Children's Sadness Management Scale (CSMS) as mentioned in this paper was developed to assess children's inhibition, dysregulated-expression, and coping with sadness experience and expression using multiple informants, reliability and validity were established based on a community sample of 227 fourth and fifth-grade children's self-report, maternal report, and peer ratings of behavior.
Abstract: Although sadness in children is a normal and transient experience, research has not investigated how children manage sadness. Understanding normative sadness management has important implications for helping children who exhibit maladaptive forms of emotional expression. The Children's Sadness Management Scale (CSMS) was developed to assess children's inhibition, dysregulated-expression, and coping with sadness experience and expression. Using multiple informants, reliability and validity were established based on a community sample of 227 fourth- and fifth-grade children's self-report, maternal report (N = 171), and peer ratings of behavior (N = 227). A three-factor solution was supported with strong internal consistency for the Inhibition scale and moderately strong internal consistency for the Emotion Regulation Coping and Dysregulated-Expression scales. Findings indicate that the CSMS provides a reliable and valid measure of normative sadness management.
320 citations
30 Jul 2001
TL;DR: This book presents new and updated techniques in forensic taphonomy, an international endeavour which includes collecting the evidence in crime scene and interpretation of dead cases and takes an interdisciplinary and international approach.
Abstract: advances in forensic taphonomy: method, theory, and the taphonomic approach within paleontology, archaeology, and paleoanthropology continues to produce advances in understanding postmortem biochemical and morphological transformations. conversely, advances in understanding the early and intermediate postmortem period generated in the forensic realm can and should be brought to the attention of scientists who study the historic and prehistoric past. advances in forensic taphonomy: method, theory, and advances in forensic taphonomy: method, theory, and archaeological perspectives william d. haglund advances in forensic taphonomy | method, theory, and the taphonomic approach within paleontology, archaeology, and paleoanthropology continues to produce advances in understanding postmortem biochemical and morphological transformations. conversely, advances in understanding the early and intermediate postmortem period generated in the forensic realm can and should be brought to the attention of scie advances in forensic taphonomy: method, theory, and advances in forensic taphonomy: method, theory, and archaeological perspectives. the taphonomic approach within paleontology, archaeology, and paleoanthropology continues to produce advances in understanding postmortem biochemical and morphological transformations. conversely, advances in understanding the early and intermediate postmortem period generated in the forensic realm can and should be brought to the attention of scientists who study the historic and prehistoric past. advances in forensic taphonomy: method, theory, and advances in forensic taphonomy: method, theory, and archaeological perspectives. by. william d. haglund (editor) 4.38 · rating details · 13 ratings · 0 reviews. the taphonomic approach within paleontology, archaeology, and paleoanthropology continues to produce advances in understanding postmortem biochemical and morphological transformations. conversely, advances in understanding the early and intermediate postmortem period generated in the forensic realm can and should be brought to the full e-book advances in forensic taphonomy: method, theory conversely, a vances in understanding the early and intermediate postmortem period generated in the forensic realm can and should be brought to the attention of scientists who study the historic and prehistoric pasting on the success of forensic taphonomy: the postmortem fate of human remains, advances in forensic taphonomy: method, theory, and archaeological perspectives presents new and updated techniques. advances in forensic taphonomy: method, theory and forensic taphonomy is an international endeavour which includes collecting the evidence in crime scene and interpretation of dead cases. forensic taphonomy is often linked with ecological aspect forensic taphonomy haglund pdf berkeley pdf advances in forensic taphonomy: method, theory, and archaeological perspectives corinna barriento marked it as to-read jul 15, amazon second chance pass it on, trade it in, give it a second life. review articles, case reports, and chapters on methodology round out this book’s unique approach to forensic science. advances in forensic taphonomy: method, theory, and this comprehensive text takes an interdisciplinary and international
285 citations
TL;DR: A framework for control of alien marine species is presented to provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation.
Abstract: The introduction of alien, or nonindigenous, animals and plants has been identified by scientists and policy makers as a major threat to biodiversity in marine ecosystems. Although government agencies have struggled to control alien species on land and freshwater for decades with mixed success, the control of alien marine species is in its infancy. Prevention of introduction and establishment must be the first priority, but many populations of alien marine species are already well established worldwide. National and interna- tional policies leave loopholes for additional invasions to occur and provide only general guidance on how to control alien species once they are established. To address this issue, a multinational group of 25 scientists and attorneys convened in 1998 to examine options for controlling established populations of alien marine species. The discussions resulted in a framework for control of alien marine species to provide decision-mak- ing guidance to policymakers, managers, scientists, and other stakeholders. The framework consists of seven basic steps: (1) establish the nature and magnitude of the problem, (2) set objectives, (3) consider the full range of alternatives, (4) determine risk, (5) reduce risk, (6) assess benefits versus risks, and (7) monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation.
260 citations
TL;DR: It is shown that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light–dark cycles and after photic input is eliminated by entraining flies to temperature cycles, indicating fundamental differences between central and peripheral oscillator mechanisms in Drosophila.
Abstract: Cryptochromes are flavin/pterin-containing proteins that are involved in circadian clock function in Drosophila and mice. In mice, the cryptochromes Cry1 and Cry2 are integral components of the circadian oscillator within the brain and contribute to circadian photoreception in the retina. In Drosophila, cryptochrome (CRY) acts as a photoreceptor that mediates light input to circadian oscillators in both brain and peripheral tissue. A Drosophila cry mutant, cryb, leaves circadian oscillator function intact in central circadian pacemaker neurons but renders peripheral circadian oscillators largely arrhythmic. Although this arrhythmicity could be caused by a loss of light entrainment, it is also consistent with a role for CRY in the oscillator. A peripheral oscillator drives circadian olfactory responses in Drosophila antennae. Here we show that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light-dark cycles and after photic input is eliminated by entraining flies to temperature cycles. These results demonstrate a photoreceptor-independent role for CRY in the periphery and imply fundamental differences between central and peripheral oscillator mechanisms in Drosophila.
TL;DR: The hypothesis that the Q223R polymorphism (but not the K109R or K656N polymorphism) of the leptin receptor gene is associated with obesity and predicts a small percentage of body weight and body composition variability in a genetically homogeneous population is supported.
Abstract: Genetic variation at the leptin receptor gene locus may play an important role in the pathophysiology of human obesity, a leptin-resistant state. Previous studies exploring potential associations between leptin receptor gene polymorphisms and obesity have reported conflicting results. The aim of this study was to evaluate a genetically homogeneous population for associations between body composition variables and three common leptin receptor gene polymorphisms (K109R, Q223R, and K656N) that have potential functional significance as well as to assess the contributions of these polymorphisms to the variability of obesity. One hundred and eighteen consecutively enrolled subjects (62 women: mean age, 17.5 ± 1.6 yr; body mass index range, 16.2–30.1; 56 men: mean age, 17.8 ± 1.8 yr; body mass index range, 15.4–35.9) were genotyped for the three polymorphisms, and their body mass index, sum of 4 skinfolds, fat-free mass, percent fat mass, serum leptin levels, caloric intake, fat intake, and exercise patterns wer...
TL;DR: In this paper, semiconducting metal oxide (SMO) film technology is used to engineer a small, robust, sensitive, and selective sensor array to detect NOx and NH3 emissions.
Abstract: In many fossil fuel burning systems, NOx emissions are minimized by a selective catalytic reduction (SCR) technique where NH3 is injected into the flue gas stream to react with NOx to form environmentally safe gases, such as nitrogen and water vapor. Unfortunately, this process is usually incomplete, resulting in either NOx emissions or excess NH3 (NH3 slip). Therefore, a critical need exits for an in situ sensor array near the stack to provide real-time control of the NH3 injection, and hence, minimize the NOx emissions released into the environment. In the present work, semiconducting metal oxide (SMO) film technology is used to engineer a small, robust, sensitive, and selective sensor array to detect NOx and NH3 emissions. Many thin film tungsten trioxide (WO3) based sensing elements were tested in order to identify two film recipes capable of sensitively and selectively detecting NOx and NH3. The critical parameters inherent in each film recipe are type of substrate material, film thickness, doping, deposition temperature, and operating temperature. The two element sensor array’s response characteristics analyzed include the response and recovery times, rates of reaction, dynamic range, sensitivity, repeatability and selectivity.
TL;DR: In this paper, the role of three characteristics of international managers, namely nationality, cultural distance, and expatriate status, for their network ties is studied, and the implications for international management theory and practice are discussed.
Abstract: We study the role of three characteristics of international managers—nationality, cultural distance, and expatriate status, for their network ties. A network analysis of cross-subsidiary interactions among 457 managers in an MNE demonstrates that managers form strong expressive ties with peers with smaller cultural distance and from the same status group. However, managers form strong instrumental ties with peers who are different on these background characteristics. The implications for international management theory and practice are discussed.
TL;DR: The luminescence of Au(I) compounds is related for the first time to Au-Au bonded excimers and exciplexes similar to those reported earlier for Ag(I), and the formation of M-M bonds in the first excited electronic states.
Abstract: Solutions of K[Au(CN)(2)] and K[Ag(CN)(2)] in water and methanol exhibit strong photoluminescence. Aqueous solutions of K[Au(CN)(2)] at ambient temperature exhibit luminescence at concentration levels of > or =10(-2) M, while frozen methanol glasses (77 K) exhibit strong luminescence with concentrations as low as 10(-5) M. The corresponding concentration limits for K[Ag(CN)(2)] solutions are 10(-1) M at ambient temperature and 10(-4) M at 77 K. Systematic variations in concentration, solvent, temperature, and excitation wavelength tune the luminescence energy of both K[Au(CN)(2)] and K[Ag(CN)(2)] solutions by >15 x 10(3) cm(-1) in the UV-visible region. The luminescence bands have been individually assigned to *[Au(CN)(2)(-)](n) and *[Ag(CN)(2)(-)](n) excimers and exciplexes that differ in "n" and geometry. The luminescence of Au(I) compounds is related for the first time to Au-Au bonded excimers and exciplexes similar to those reported earlier for Ag(I) compounds. Fully optimized unrestricted open-shell MP2 calculations for the lowest-energy triplet excited state of staggered [Au(CN)(2)(-)](2) show the formation of a Au-Au sigma single bond (2.66 A) in the triplet excimer, compared to a weaker ground-state aurophilic bond (2.96 A). The corresponding frequency calculations revealed Au-Au Raman-active stretching frequencies at 89.8 and 165.7 cm(-1) associated with the ground state and lowest triplet excited state, respectively. The experimental evidence of the exciplex assignment includes the extremely large Stokes shifts and the structureless feature of the luminescence bands, which suggest very distorted excited states. Extended Huckel (EH) calculations for [M(CN)(2)(-)](n) and *[M(CN)(2)(-)](n) models (M = Au, Ag; n = 2, 3) indicate the formation of M-M bonds in the first excited electronic states. From the average EH values for staggered dimers and trimers, the excited-state Au-Au and Ag-Ag bond energies are predicted to be 104 and 112 kJ/mol, respectively. The corresponding bond energies in the ground state are 32 and 25 kJ/mol, respectively.
TL;DR: In this article, the authors examined the coverage of mineral surfaces by organic matter (OM) in acid soils of Massachusetts and found that the bulk of surface area exposed in most untreated samples consists of mineral rather than organic material.
Abstract: Soil organic matter (OM) and mineral surfaces are intimately related, affecting the dynamics of each and their reactivity with many environmentally important substances. We examined the coverage of mineral surfaces by OM in acid soils of Massachusetts. Specific surface areas are controlled by a combination of clay and sesquioxide contents. Subsurface horizons, especially C horizons with pH 4.6 to 4.8, contained a phase with significant microporosity (pores <2 nm) that could be eliminated by 350°C muffling. Organic C (OC) concentrations in surficial (A, O) horizons have surface area-normalized loadings usually above the monolayer-equivalent (ME) level (1 mg OC m -2 ), while B and C horizons usually have loadings at this level. Surface area-normalized loadings are inversely related to pH for each horizon type. Samples with high loadings show occlusion of the bulk of mineral surface area by OM, as evidenced by release of significant surface area after OM removal. However, a new method of assessing OM coverage of exposed surfaces, using the energetics of gas adsorption, indicate that the bulk of surface area exposed in most untreated samples consists of mineral rather than organic material. The data are consistent with a model in which the occluding OM is present in a low-surface area configuration, such as organoclay aggregates, rather than as dispersed coatings on mineral grains.
TL;DR: The manuscript develops a benefit estimation method to measure the welfare impacts of providing nutrient information, which significantly affects purchase behaviour but may not lead to increased consumption of health foods.
Abstract: Cost/benefit analysis justifies regulations altering the amount of health-related information presented to consumers. The current method of benefit analysis, the cost of avoided illness, is limited; it assumes the benefits of health-related information are adequately represented by changes in illnesses. The manuscript develops a benefit estimation method to measure the welfare impacts of providing nutrient information. Nutrient labeling significantly affects purchase behaviour but may not lead to increased consumption of health foods. Nutrient labeling may increase welfare without any change in health risk. Thus, the cost of avoided illness approach can underestimate the social benefits of providing nutrient information. Copyright 2001, Oxford University Press.
TL;DR: A new compilation of annually resolved time series of atmospheric trace gas concentrations, solar irradiance, tropospheric aerosol optical depth, and stratospheric (volcanic) optical depth is presented for use in climate modeling studies of the period 1500 to 1999 A.D..
Abstract: A new compilation of annually resolved time series of atmospheric trace gas concentrations, solar irradiance, tropospheric aerosol optical depth, and stratospheric (volcanic) aerosol optical depth is presented for use in climate modeling studies of the period 1500 to 1999 A.D. Atmospheric CO 2 , CH 4 , and N 2 O concentrations over this period are well established on the basis of fossil air trapped in ice cores and instrumental measurements over the last few decades. Estimates of solar irradiance, ranging between 1364.2 and 1368.2 W/m 2 , are presented using calibrated historical observations of the Sun back to 1610, along with cosmogenic isotope variations extending back to 1500. Tropospheric aerosol distributions are calculated by scaling the modern distribution of sulfate and carbonaceous aerosol optical depths back to 1860 using reconstructed regional CO 2 emissions; prior to 1860 the anthropogenic tropospheric aerosol optical depths are assumed to be zero. Finally, the first continuous, annually dated record of zonally averaged stratospheric (volcanic) optical depths back to 1500 is constructed using sulfate flux data from multiple ice cores from both Greenland and Antarctica, in conjunction with historical and instrumental (satellite and pyrheliometric) observations. The climate forcings generated here are currently being used as input to a suite of transient (time dependent) paleoclimate model simulations of the past 500 years. These forcings are also available for comparison with instrumental and proxy paleoclimate data of the same period.
TL;DR: It is suggested that Jagged regulation of cell-cell and cell-matrix interactions may contribute to the control of cell migration in situations of tissue remodeling in vivo.
Abstract: The Jagged/Notch signaling pathways control cell fate determination and differentiation, and their dysfunction is associated with human pathologies involving cardiovascular abnormalities. To determine the presence of these genes during vascular response to injury, we analyzed expression of Jagged1, Jagged2, and Notch1 through 4 after balloon catheter denudation of the rat carotid artery. Although low levels of Jagged1, Jagged2, and constitutive expression of Notch1 were seen in uninjured endothelium, expression of all was significantly increased in injured vascular cells. High Jagged1 expression was restricted to the regenerating endothelial wound edge, whereas Notch transcripts were abundant in endothelial and smooth muscle cells. To understand the basis for Jagged/Notch control of cellular phenotype, we studied an in vitro model of NIH3T3 cells transfected with a secreted form of the extracellular domain of Jagged1. We report that the soluble Jagged1 protein caused decreased cell-matrix adhesion and cell migration defects. Cadherin-mediated intercellular junctions as well as focal adhesions were modified in soluble Jagged1 transfectants, demonstrating that cell-cell contacts and adhesion plaques may be targets of Jagged/Notch activity. We suggest that Jagged regulation of cell-cell and cell-matrix interactions may contribute to the control of cell migration in situations of tissue remodeling in vivo.
TL;DR: The degradative ability of an ultrafiltered low molecular weight preparation of chelating compounds isolated from the brown-rot fungus Gloeophyllum trabeum (termed 'Gt chelator') is shown, which suggests that chelators from the fungus may be able to sequester iron from cellulose and reduce it in near proximity to the cellulose to better promote depolymerization.
TL;DR: WC finds that people frequently use “ties” in rcsponsc to rating questions and that the option not to choose any of the alternatives (“opt-out”) affects some prefcrcnce cstimales.
Abstract: A split-sample design is used to cvnluatc the convergent validity of three rcsponsc formats used in conjoint analysis experiments. WC investigate whether recoding rating data to rankings and chooscone formats. and recoding rranking data to choose one. result in structural models and welfare estimates that arc statistically indistinguishalde from estimates based on ranking or C~OOSC-one questions. Our results indicate that convergent validity of ratings, ranks, and choose one is not established. in addition, WC: find that people frequently use “ties” in rcsponscs to rating questions. and that the option not to choose any of the alternatives (“opt-out”) affects some prefcrcnce cstimales.
TL;DR: In this article, the authors investigated the habitat use and movements of two turtle species to assess the importance of conserving multiple wetlands and the upland matrix in which they occur, using resightings of marked individuals (69 spotted, 16 Blanding's) and radiotelemetry (13 manchadas, 16 de Blanding, radiomarcadas por 1-2 temporadas) to investigate the movements and habitat use of both species.
Abstract: We investigated the habitat use and movements of two turtle species to assess the importance of conserving multiple wetlands and the upland matrix in which they occur. Spotted turtles ( Clemmys guttata) and Blanding's turtles ( Emydoidea blandingii) are considered threatened and endangered, respectively, in Maine where they are near the northeastern periphery of their geographic range. We used resightings of marked individuals (69 spotted, 16 Blanding's) and radiotelemetry (13 spotted, 9 Blanding's, radiotagged for one or two seasons) to investigate the movements and habitat use of both species. Individuals of both species used multiple wetlands throughout the year, including permanent and seasonal pools, forested swamps, and wet meadows. Pools occupied by spotted and Blanding's turtles were small (<0.4 ha), and they were less isolated from other wetlands than pools that did not contain turtles. Both species used uplands extensively for nesting, dormancy, and traveling between wetlands. Turtles traveled 70–570 m (spotted) and 100–1620 m ( Blanding's) to nest, and nests were located 1–120 m (spotted) and 70–410 m ( Blanding's) from the nearest wetland. Spotted and Blanding's turtles entered relatively dormant stages for 15–89 and 3–21 consecutive days, respectively, and upland dormancy sites were 12–80 m (spotted) and 30–110 m ( Blanding's) from the nearest wetland. Total distance traveled overland throughout a season was 0–1680 m and 0–6760 m for radiotagged spotted and Blanding's turtles, respectively. Most spotted turtles followed a seasonal pattern of habitat use: pools for spring activity, upland forest for relative dormancy during part of the summer, and wet meadows or forested swamps for overwintering. A seasonal pattern in the habitat use of Blanding's turtles was not as evident. Our study suggests that protecting small wetlands, maintaining generous terrestrial buffers around individual wetlands, and conserving wetlands in groups are important components of a landscape approach to species conservation.
Resumen: Investigamos el uso de habitat y los movimientos de dos especies de tortugas para evaluar la importancia de conservar multiples humedales y la matriz terrestre en la que ocurren. Tortugas manchadas (Clemmys guttata) y tortugas de Blanding ( Emydoidea blandingii) estan consideradas como amenazadas y en peligro, respectivamente, en Maine donde se encuentran cerca de la periferia noreste de su rango geografico. Utilizamos reavistamientos de individuos marcados (69 manchadas, 16 de Blanding ) y radiotelemetria (13 manchadas, 9 de Blanding, radiomarcadas por 1-2 temporadas) para investigar los movimientos y uso de habitat de ambas especies. Los individuos de ambas especies utilizaron multiples humedales a lo largo del ano incluyendo charcas permanentes y temporales, cienagas boscosas y praderas inundadas. Las charcas ocupadas por tortugas manchadas y de Blanding fueron pequenas (<4 ha), y estaban menos aisladas de los demas humedales que no contenian tortugas. Ambas especies usaron terrenos elevados extensivamente para anidar, para los periodos de aletargamiento, para moverse entre humedales. Las tortugas viajaron entre 50 y 570 m (manchadas) y entre 100 y 1620 m (de Blanding ) para anidar, y los nidos se localizaron entre 1 y 120 m (manchadas) y entre 70 y 410 m (de Blanding ) del humedal mas cercano. Las tortugas manchadas y de Blanding entraron en etapas relativo de letargo por 15-89 y 3-21 dias consecutivos, respectivamente, y los sitios de letargo estaban entre 12 y 80 m (manchadas) y 30 y 110 m (de Blanding ) del humedal mas cercano. La distancia total recorrida en tierra en una temporada vario entre 0 y 1680 m y entre 0 y 6760 m para las tortugas manchadas y de Blanding radiomarcadas respectivamente. La mayoria de las tortugas manchadas tuvieron un patron estacional de uso del habitat: charcas para la actividad de primavera, bosque elevado cuando la etapa en letargo la etapa de lefargo relativo durante parte del verano y praderas inundadas o cienagas boscosas durante el invierno. En los movimientos de la tortuga de Blanding no fue evidente un patron estacional de uso de habitat. Nuestro estudio sugiere que la proteccion de humedales pequenos, la presencia de amortiguadores terrestres alrededor de los humedales y la conservacion de humedales en grupos son componentes importantes de una aproximacion de paisaje a la conservacion de especies.
TL;DR: The experiments demonstrated that Batrachochytrium dendrobatidis can be a fatal pathogen in poison dart frogs and the experimentally-induced disease in these frogs resembled cases of cutaneous chytridiomycosis that have recently been described in several other species of captive and wild amphibians.
Abstract: In a series of three experiments during March–October, 1998, two species of captive-bred poison dart frogs (Dendrobates tinctorius and D. auratus) were exposed to Batrachochytrium dendrobatidis, a recently-described chytridiomycete fungus (chytrid) that was originally isolated from a blue poison dart frog (D. azureus). All frogs exposed to the chytrids developed a fatal skin disease, whereas none of the control frogs developed skin lesions. The most consistent clinical sign in chytrid-exposed frogs was excessive shedding of skin. Gross lesions were subtle, usually affected the legs and ventrum, and consisted of mild skin thickening and discoloration. Microscopic examination of shed skin pieces and/or skin imprints demonstrated the presence of chytrids and was used for ante mortem and post mortem confirmation of chytrid infection. Histologically, there was epidermal hyperkeratosis, hyperplasia, and hypertrophy associated with low to moderate numbers of chytrids in the keratinized layers. These experiments ...
Mount Holyoke College1, University of Missouri2, University of Kentucky3, Rutgers University4, Southern Methodist University5, Harvard University6, University of Maine7, Arizona State University8, Miami University9, University of New Mexico10, Rice University11, University of Houston12, National Institute of Standards and Technology13
TL;DR: The first results from a suite of large, gem crystals which cover a broad spectrum of minerals in which light elements are major constituents using both in situ and wet chemical techniques were reported in this paper.
Abstract: The quantitative determination of light element concentrations in geological specimens represents a major analytical challenge as the electron probe is generally not suited to this task With the development of new in situ analytical techniques, and in particular the increasing use of secondary ion mass spectrometry, the routine determination of Li, Be and B contents has become a realistic goal However, a major obstacle to the development of this research field is the critical dependence of SIMS on the availability of well characterized, homogeneous reference materials that are closely matched in matrix (composition and structure) to the sample being studied Here we report the first results from a suite of large, gem crystals which cover a broad spectrum of minerals in which light elements are major constituents We have characterized these materials using both in situ and wet chemical techniques The samples described here are intended for distribution to geochemical laboratories active in the study of light elements Further work is needed before reference values for these materials can be finalized, but the availability of this suite of materials represents a major step toward the routine analysis of the light element contents of geological specimens
La determination quantitative des concentrations en elements legers dans les echantillons geologiques represente un defi analytique majeur, la sonde electronique ne convenant generalement pas pour ce travail Avec le developpement de nouvelles techniques analytiques in situ, en particulier l'utilisation grandissante de la spectrometrie ionique secondaire, la determination en routine des teneurs en Li, Be et B est devenue un objectif realiste Toutefois, un obstacle majeur dans le developpement de cette recherche subsiste : la technique SIMS est dependante de la disponibilite de materiaux de reference bien caracterises et homogenes proches en composition et en structure de l'echantillon etudie Nous rapportons ici les premiers resultats obtenus a partie d'un groupe de grands cristaux de qualite gemme recouvrant un large spectre de mineraux composes essentiellement d'elements legers Nous avons caracterise ces materiaux en utilisant a la fois des techniques in situ et par voie humide Les echantillons decrits ici vont etre distribues dans les laboratoires de geochimie specialises dans l'etude des elements legers Avant la conclusion des valeurs de reference de ces materiaux, des travaux ulterieurs seront necessaires, mais la disponibilite de l'ensemble de ces materiaux represente une etape importante vers l'analyse en routine des teneurs en elements legers d'echantillons geologiques
TL;DR: Age-related changes in morphology and physiology are inherent in meristems and persist for at least 3 years in scions grafted to juvenile rootstock in a population of red spruce.
Abstract: The contribution of changes in meristem behavior to age-related decline in forest productivity is poorly understood. We studied age-related trends in needle morphology and gas exchange in a population of red spruce (Picea rubens Sarg.) growing in a multi-cohort stand where trees ranged from first-year germinants to trees over 150 years old, as well as in grafted scions from these trees. In the field study, age-related trends in foliar morphology were determined in six cohorts ranging in age from 2 to 120 years, and differences in gas exchange characteristics were compared between 60- and 120-year age classes. In a common-rootstock study, scions from trees representing 20-, 60-, and 120-year cohorts were grafted onto juvenile rootstock and maintained for three growing seasons, after which morphological and physiological foliar attributes were evaluated. The field study revealed significant age-related trends in foliar morphology, including decreasing specific leaf area, and increasing needle width, projected area, and width/length ratio. Similar trends were apparent in foliage from the grafted scions. Both in situ foliage and shoots of grafted scions from the oldest cohort showed significantly lower photosynthetic rates than their counterparts from younger trees; however, differences in stomatal conductance and internal CO(2) concentrations were not significant. These results suggest that: (1) foliage of red spruce exhibits age-related trends in both morphology and physiology; (2) age-related decreases in photosynthetic rates contribute to declining productivity in old red spruce; (3) declines in photosynthetic rates result from nonstomatal limitations; and (4) age-related changes in morphology and physiology are inherent in meristems and persist for at least 3 years in scions grafted to juvenile rootstock.
TL;DR: Pollen records from three sites in the Lake District of southern Chile are reported, from which it is inferred conditions similar to modern climate between about 13 and 12.2 14C kyr before present (bp), followed by cooling events at about 12.3 and 11.4Ckyr, supporting the idea that interhemispheric linkage through the atmosphere was the primary control on climate during the last deglaciation.
Abstract: Understanding the relative timings of climate events in the Northern and Southern hemispheres is a prerequisite for determining the causes of abrupt climate changes. But climate records from the Patagonian Andes1,2,3,4 and New Zealand5,6,7,8 for the period of transition from glacial to interglacial conditions—about 14.6–10 kyr before present, as determined by radiocarbon dating—show varying degrees of correlation with similar records from the Northern Hemisphere. It is necessary to resolve these apparent discrepancies in order to be able to assess the relative roles of Northern Hemisphere ice sheets and oceanic, atmospheric and astronomical influences in initiating climate change in the late-glacial period. Here we report pollen records from three sites in the Lake District of southern Chile (41° S) from which we infer conditions similar to modern climate between about 13 and 12.2 14C kyr before present (bp), followed by cooling events at about 12.2 and 11.4 14C kyr bp, and then by a warming at about 9.8 14C kyr bp. These events were nearly synchronous with important palaeoclimate changes recorded in the North Atlantic region9, supporting the idea that interhemispheric linkage through the atmosphere was the primary control on climate during the last deglaciation. In other regions of the Southern Hemisphere, where climate events are not in phase with those in the Northern Hemisphere, local oceanic influences may have counteracted the effects that propagated through the atmosphere.
TL;DR: The authors found that women report greater role balance when their level of parental attachment to children is higher and when their marital satisfaction is greater, but gendered time use gives rise to important differences.
Abstract: We generate models predicting wives' and husbands' feelings of overall balance across roles. Drawing on fine-grained data about marital lifestyles and time use, we find few predictors that are the same for both partners. Both report greater role balance when their level of parental attachment to children is higher and when their marital satisfaction is greater, but gendered time use gives rise to important differences. Wives report greater balance when they have more paid work hours but have fewer of these hours on weekends. Wives' balance is also greater when they feel less financial strain, have less leisure time alone with their children, more couple leisure alone with their husbands, and more social network involvement. Husbands' contribute to wives' balance when they report more relationship maintenance in the marriage and more leisure with their children at those times when wives are not present. Husbands' own role balance increases as their income rises, but it decreases as their work hours rise. Husbands' balance also rises with more nuclear family leisure, and it lessens as their leisure alone increases. Our discussion highlights the ways that gendered marital roles lead to these different correlates of balance. Key Words: gender, leisure, marriage, multiple roles, parenthood, role balance, work. Married adults typically must juggle their marriage with parenthood, paid work, housework, kinship, friendship, and leisure interests. This complexity has been seen as creating stress, conflict, and overload (Goode, 1960; Netemeyer, Boles, & McMurrian, 1996), but also stimulation and challenge (Barnett & Rivers, 1996). In turn, role theories have offered different perspectives on how people solve the juggling problem. Some analysts see a hierarchy of roles as inevitable, claiming that people put more time and energy into those activities that are most highly valued (e.g., McCall & Simmons, 1978; Reitzes & Mutran, 1994; Stryker, 1980; Thoits, 1992). In contrast, Marks and MacDermid (1996) question the inevitability of this hierarchical self-organization. They concede that some people invest more in some roles and give scant attention to others (as seen, for example, in workaholics' addiction to work). Nevertheless, many people may be more evenhanded in allocating their personal resources among their various roles, a phenomenon Marks and MacDermid termed role balance to signal this nonhierarchical option. Role balance is a cognifive-affective orientation, or "internal working model," reflecting the "tendency to become fully engaged in the performance of every role in one's total role system, to approach every typical role and role partner with an attitude of attentiveness and care" (p. 421). WHAT WE KNOW ABOUT ROLE BALANCE Despite the popular interest in balancing roles, there is a surprising lack of research. Studies of the work-family interface have accumulated, but they tend to dwell on the interference of each domain with the other (Pleck, 1995). For example, early studies found that for men with the coronary-prone "type A' behavior pattern, jobs have a negative impact on home life and on wives' emotional well-being (Burke, Weir, & DuWors, 1980). Voydanoff (1988) looked both at job demands and at family demands as contributors to work-family conflict. More recent studies have offered a bidirectional model, focusing both on how work interferes with family and how family interferes with work (Frone, Russell, & Cooper, 1992; Frone, Yardley, & Markel, 1997). In all this research, however, the watchword is interference, and the prospect of balancing the different domains is left as an unexplored residual category. Balance becomes the absence of something negative rather than something positive that might be experienced in its own right. Although this interference notion of the different role domains has gotten more attention, an enhancement perspective has also sought recognition (Pleck, 1995). …
TL;DR: The absence of specific, high-affinity binding of the prototypical AHR ligands TCDD and BNF, is a property shared by known invertebrate AHR homologues, distinguishing them from vertebrates AHRs.